extends Node
## Drives VRM facial expression blendshapes based on emotion signals.
## Smoothly interpolates between 6 base emotions.

const NodeUtilsScript = preload("res://src/core/node_utils.gd")

const BLEND_SPEED: float = 8.0

const EMOTION_SHAPES: Array[String] = [
	"happy",
	"sad",
	"angry",
	"surprised",
	"relaxed",
	"neutral",
]

var _mesh: MeshInstance3D
var _blend_indices: Dictionary = {}
var _target_weights: Dictionary = {}
var _current_weights: Dictionary = {}
var _current_emotion: String = "neutral"


func setup(model: Node3D) -> void:
	_mesh = NodeUtilsScript.find_first_mesh_with_blendshapes(model)
	if _mesh == null:
		push_warning("ExpressionController: No mesh found")
		return

	for emotion: String in EMOTION_SHAPES:
		var idx := NodeUtilsScript.find_blend_shape_index(_mesh, emotion)
		if idx == -1:
			idx = NodeUtilsScript.find_blend_shape_index(_mesh, emotion.capitalize())
		if idx == -1:
			idx = NodeUtilsScript.find_blend_shape_index(_mesh, emotion.to_upper())
		if idx != -1:
			_blend_indices[emotion] = idx
		_target_weights[emotion] = 0.0
		_current_weights[emotion] = 0.0

	_set_emotion("neutral")
	EventBus.emotion_changed.connect(_on_emotion_changed)


func _process(delta: float) -> void:
	if _mesh == null:
		return

	var speed := BLEND_SPEED * delta
	for emotion: String in EMOTION_SHAPES:
		var target: float = _target_weights[emotion]
		var current: float = _current_weights[emotion]
		if absf(current - target) > 0.001:
			current = lerpf(current, target, speed)
			_current_weights[emotion] = current
			if _blend_indices.has(emotion):
				_mesh.set_blend_shape_value(_blend_indices[emotion], current)


func _set_emotion(emotion: String) -> void:
	_current_emotion = emotion
	for shape: String in EMOTION_SHAPES:
		_target_weights[shape] = (1.0 if shape == emotion else 0.0)


func _on_emotion_changed(emotion: String) -> void:
	if emotion in EMOTION_SHAPES:
		_set_emotion(emotion)
	else:
		_set_emotion("neutral")